This invention relates to the production of ravioli and similar filled dough food products. More particularly, the invention relates to a machine for producing ravioli containing a thickened viscous filling material in a high speed commercial operation.
Basically in the production of ravioli, measured portions of filling material, such as cheese, ground meat, and the like, are introduced between two moving sheets of dough and the dough sheets are then pressed together to form pockets enclosing individual portions of filling material. Machines for producing ravioli are well known in the art. For example, U.S. Pat. Nos. 4,848,218 to Battaglia; 3,605,641 to Shuster; 2,774,313 to Lombi; and 2,227,728 to Lombi each disclosure a machine for producing ravioli. Typically such machines include a pair of dough hoppers, a filling material hopper located between the dough hoppers and means for forming dough sheets which are fed into the nip between two rolls, i.e., a die roll having a plurality of mold cavities and an anvil roll. A cutting roll is mounted adjacent the die roll to cut the sealed dough sheets into individual ravioli pieces. Filling material is introduced into dough-lined cavities in the die roll through tubular feeding nozzles mounted in the base of the filling material hopper, with the filling material being pumped from the hopper by gear pumps, air cylinders, pistons, and the like. In such prior machines, the tubular feeding nozzles have been mounted in a number of ways, for example, for vertical movement toward and away from the die roll (U.S. Pat. No. 2,774,313), in a fixed position adjacent the die roll (U.S. Pat. No. 3,605,641), and for oscillating movement (U.S. Pat. No. 4,848,218). The timing of all functions of such machines is typically controlled by conventional gearing to coordinate the discharge of filling material from the feeding nozzles into the dough-lined mold cavities in the die roll.
In recent years, the marketing of refrigerated pasta products, including ravioli, has become of increasing commercial significance. Ravioli produced for refrigerated marketing differs from that produced for marketing in a canned or frozen state in that the dough and filling components are formulated to have a lower moisture content to facilitate the production of ravioli having an extended shelf life. However, the use of such lower moisture components has given rise to a number of problems in the production of the ravioli in a high speed commercial operation using ravioli machines of the prior art. For example, the reduced moisture filling material has a viscosity significantly higher than that of conventional ravioli filling material. This high viscosity filling material is difficult to pump from the hopper in which it is stored into the mold cavities using the gear pumps, air cylinders, and pistons of prior art machines without damaging the texture of the filling material. In addition, the tubular feeding nozzles of prior art machines are not adapted to handle high viscosity filling material, making it difficult to accurately control the amount of filling material deposited and to prevent the deposit of the filling material onto portions of the dough sheet outside the dough-lined mold cavities.